Question

Find the sum of the following A.P upto 20 terms 9,17,25____

Answer 1

$\large\bf\underline\purple{Given:-}$

• A.P = 9, 17, 25.........

$\large\bf\underline\purple{To\:Find:-}$

• Sum of 20 terms

$\large\bf\underline\purple{Solution:-}$

From the given data , we have

n = 20

a = 9

d = 17 - 9 = 8

We know,

➝ Sn = 2a + (n - 1) d

= 2 × 20 + ( 20 - 1) × 8

= 40 + 152

= 192

PLEASE MARK IT BRAINILIEST

Answer 2

Answer:

Sn = 2a + (n - 1) d

S20 = 2 × 9 + ( 20 - 1) × 8

= 18 + 152

S20 = 170

PLEASE MARK IT BRAINILIEST